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Full text of "AFPA: National Design Specification for Wood Construction With Supplemental Design Values for Wood Construction"





By Authority Of 

THE UNITED STATES OF AMERICA 

Legally Binding Document 



By the Authority Vested By Part 5 of the United States Code § 552(a) and 
Part 1 of the Code of Regulations § 51 the attached document has been duly 
INCORPORATED BY REFERENCE and shall be considered legally 
binding upon all citizens and residents of the United States of America. 
HEED THIS NOTICE : Criminal penalties may apply for noncompliance. 





Document Name: AFPA: National Design Specification for Wood 

Construction With Supplemental Design Values for 
Wood Construction 
24 CFR 3280.304(b)(1) 



CFR Section(s): 



Standards Body: 



2001 EDITION 



ANSI/AF&PA NDS-2001 

(revised standard) 
Approval Date: November 30, 2001 




ATIONAL DESIGN SPECIFICATIO 



FOR WOOD CONSTRUCTION 



American 
Forest & 
Paper 
Association 



American Wood Council 




NATIONAL DESIGN SPECIFICATION 3 

FOR WOOD CONSTRUCTION 



Copyright €> 2001 
American Forest & Paper Association. Inc. 



NDS2002 FM.pmd 




3/1 3/02. 11:00 AM 



NATIONAL DESIGN SPECIFICATION FOR WOOD CONSTRUCTION 



FOREWORD 



The National Design Specification"" for Wood Con- 
struction (NDS S ) was first issued by the National Lumber 
Manufacturers Association (now the American Forest & 
Paper Association) (AF&PA) in 1944, under the title Na- 
tional Design Specification for Stress-Grade Lumber and 
Its Fastenings. By 1971 the scope of the Specification 
had broadened to include additional wood products. In 
1977 the title was changed to reflect the new nature of the 
Specification, and the content was rearranged to simplify 
its use. The 1991 edition was reorganized in an easier to 
use "equation format", and many sections were rewritten 
to provide greater clarity. 

In 1992, Af&PA (formerly the National forest Prod- 
uct.s Association) was accredited as a canvass sponsor by 
the American National Standards Institute (ANSI). The 
Specification subsequently gained approval as an Ameri- 
can National Standard designated ANSI/NfoPA 
NDS-1991 with an approval date of October 16, 1992. 
The current edition of the Standard is designated ANSI/ 
AF&PA NDS-2001with an approval date ofl^oyembgr 
30.2001. 

In developing the provisions ol' this Specification, the 
most reliable data available from laboratory tests and ex- 
perience with structures in service have been carefully 
analyzed and evaluated tor the purpose of providing, in 
convenient form, a national standard of practice. 

It is intended that this Specification be used in con- 
junction with competent engineering design, accurate 
fabrication and adequate supervision of construction. 
Particular attention is directed to Section 2.1.2. relating 
to the designer's responsibility to make adjustments for 
particular end uses of structures. 



Since the first edition of the National Design Specifi- 
cation in 1944, the Association's Technical Advisory 
Committee has continued to study and evaluate new data 
and developments in wood design. Subsequent editions 
of the Specification have included appropriate revisions 
to provide for use of such new information. This edition 
incorporated numerous changes as a result of the ANSI/ 
Af&PA Canvass Committee's consideration of recom- 
mended changes by industry and others. The contributions 
of the members of this Committee to improvement of the 
Specification as a national design standard for wood con- 
struction are especially recognized. 

Acknowledgement is made to the Forest Products 
Laboratory. U.S. Department of Agriculture, for data and 
publications generously made available, and to the engi- 
neers, scientists and other users who have suggested 
changes in the content of the Specification. The Associa- 
tion invites and welcomes comments, inquiries, 
suggestions and new data relative to the provisions of this 
document. 

It is intended that this document be used in conjunc- 
tion with competent engineering design, accurate 
fabrication, and adequate supervision of construction. 
Af&PA does not assume any responsibility lor errors or 
omissions in the document, nor lor engineering designs, 
plans, or construction prepared from it. 

Those using this standard assume all liability arising 
from its use. The design of engineered structures is within 
the scope of expertise of licensed engineers, architects, or 
other licensed professionals for applications to a particu- 
lar structure. 

American Forest & Paper Association 



AMERICAN FOREST & PAPER ASSOCIATION 



NDS2002 FM.pmd 




3/1 3/02. 11:00 AM 



NATIONAL DESIGN SPECIFICATION FOR WOOD CONSTRUCTION 




TABLE OF CONTENTS 



Partmtle 



Page 



Partmtla 



General Requirements for 
Structural Design 



i.i 

1.2 
1.3 
1.4 
1.5 
1.6 



Scope 

General Requirements 
Standard as a Whole 
Design Loads 
Specifications and Plans 
Notation 



Design Values for Structural 
Members 



2. 1 General 

2.2 Design Values 

2.3 Adjustment of Design Values 

Design Provisions and 
Equations 

3. 1 General 

3.2 Bending Members - General 

3.3 Bending Members - Flexure 

3.4 Bending Members - Shear 

3.5 Bending Members - Dellection 

3.6 Compression Members - General 

3.7 Solid Columns 

3.8 Tension Members 

3.9 Combined Bending and Axial 
Loading 

3.10 Design lor Bearing 



4 Sawn Lumber 



.1 

2 
2 
2 
2 
3 
3 



,7 

8 
8 
8 



4. 1 General 

4.2 Design Values 

4.3 Adjustment ol" Design Values 

4.4 Special Design Considerations 



11 

12 
13 



1 8 
18 
19 
20 

21 

22 



23 

24 
25 
26 
28 



Structural Glued Laminated 
Timber 31 

5. 1 General 32 

5.2 Design Values 33 

5.3 Adjustment ol" Design Values 33 

5.4 Special Design Considerations 35 



Round Timber Poles and 
Piles 



6.1 General 

6.2 Design Values 

6.3 Adjustment ol' Design Values 



37 

38 
38 
38 



7 Prefabricated Wood l-Joists 43 



8 



7.1 General 

7.2 Design Values 

7.3 Adjustment ol' Design Values 

7.4 Special Design Considerations 

Structural Composite 
Lumber 



8. 1 General 

8.2 Design Values 

8.3 Adjustment ol' Design Values 

8.4 Special Design Considerations 

9 Wood Structural Panels 

9. 1 General 

9.2 Design Values 

9.3 Adjustment ol' Design Values 

9.4 Design Considerations 

10 Mechanical Connections 

10.1 General 

10.2 Design Values 

10.3 Adjustment ol' Design Values 



44 
44 
44 
45 



47 

48 
48 
48 
50 

51 

52 
52 
53 
53 

55 

56 
57 
57 



11 Dowel-Type Fasteners 65 



n.i 



1 1.4 



1 1 



General 66 

Withdrawal Design Values 68 

Lateral Design Values 7 1 
Combined Lateral and Withdrawal 

Loads 76 

Adjustment ol" Design Values 76 

Multiple Fasteners 79 



12 Split Ring and Shear Plate 

Connectors 103 



12.1 General 

12.2 Design Values 

12.3 Placement ol' Split Ring and 
Shear Plate Connectors 



104 
105 

1 I 1 



AMERICAN FOREST & PAPER ASSOCIATION 



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TABLE OF CONTENTS 



Patt/Trtle 



Pas 



Part/Title 



Page 



13 Timber Rivets 115 

13.1 General 116 

13.2 Design Values 116 

13.3 Placement ol~ Timber Rivets 118 

14 Shear Walls and 
Diaphragms 127 

14.1 Genera] 128 

14.2 Design Principles 128 

14.3 Shear Walls 128 

14.4 Diaphragms 129 

15 Special Loading Conditions 131 

15.1 Lateral Distribution Of a 
Concentrated Load 132 

15.2 Spaced Columns 132 

15.3 Built-L'p Columns 134 

1 5.4 Wood Columns With Side 

Loads and Eccentricity 137 

16 Fire Design of Wood 
Members 139 

16.1 General 140 

16.2 Design Proceedings lor Exposed 

Wood Members 140 

16.3 Wood Connections 141 



Appendix 143 

Appendix A (Non-mandatory ) 

Construction and Design Practices 144 
Appendix B ( Non-mandatory ) 

Load Duration 146 
Appe nd ix C ( N on- mandatory ) 

Temperature Effects 148 
Appendix D (Non-mandatory) 

Lateral Stability of Beams 149 
Appendix E (Non -mandatory) 

Local Stresses in Fastener Groups 150 
Appendix E ( N o n- m a nd at o ry ) 

Design lor Creep and Critical Deflection 

Applications 154 
Appendix G (Non-mandatory ) 

Effective Col u mn Length 1 5 6 

Appendix H (Non-mandatory) 

Lateral Stability of Columns 157 
Appendix I ( N o n - ma n d at o ry ) 

Yield Limit Equations lor Connections 158 
Appendix J (Non-mandatory) 

Solution of Hankinson Formula 161 
Appendix K. (Non-mandatory) 

Typical Dimensions lor Split Ring 

and Shear Plate Connectors 164 
Appendix L (Non-mandatory) 

Typical Dimensions lor Standard 

Hex Bolls 165 
Hex Lag Screws 166 
Wood Screws 167 
Common, Box and Sinker Nails 168 
Appendix M (Non-mandatory) 

Ma nu fact u ring Tolerances lor Rivets 

and Steel Side Plates for Timber 

Rivet Connections (See Chapter 13) 169 

References 171 

References 1 72 



AMERICAN WOOD COUNCIL 



NDS2002 FM.pmd 




3..'ia-02. 11:00 AM 



NATIONAL DESIGN SPECIFICATION FOR WOOD CONSTRUCTION 



LIST OF TABLES 



2.3.2 Frequently Used Load Duration 

Factors, C D 1 

2.3.3 Temperature Factor. C, 'J 

3.3.3 Effective Length. (;.. for Bending Members .. 14 

3.3.4 Form Factors, C, 15 

3.1 0.4 Bearing Area Factors. C, 22 

4.3.1 Applicability oi Adjustment Factors for 

Sawn Lumber 27 

4.3.8 Incising Factors. C, 27 

5.1 .3 Net Finished Widths of Glued 

Laminated Timbers 32 

5.3.1 Applicability of Adjustment Factors for 

Glued Laminated Timber 34 

6A Design Values for Treated Round 

Timber Piles 39 

6B Design Values for Poles Graded in 

Accordance with ASTM D3200 M 

6.3.1 Applicability of Adjustment Factors for 

Round Timber Poles and Piles 39 

6.3.5 Untreated Factors. C u . for Timber Poles 

and Piles 40 

6.3. 1 2 Single Pile Factors. C. p . for Round 

Timber Piles 41 

7.3.1 Applicability of Adjustment Factors for 

Prefabricated Wood I-Joisls 44 

8.3.1 Applicability oi Adjustment Factors for 

Structural Composite Lumber 49 

9.3.1 Appl ic a bi 1 i ty o f Adj u s tme nt Fac tors for 

Wood Structural Panels 53 

10.3.1 Applicability of Adjustment Factors for 

Connections 58 

1 0.3.3 Wet Service Factors, C M , for Connections 59 

1 0.3.4 Temperature Factors, C [5 for Connections 59 

10.3.6A Group Action Factors. C„, for Bolt or 
Lag Screw Connections With Wood 
Side Members 62 



10.3.6B Group Action Factors. C,,. for 4" Split 
Ring or Shear Plate Connectors With 
Wood Side Members 62 

10.3.6C Group Action Factors. C,. for Bolt or 
Lag Screw Connections With Steel 
Side Plates 63 

10.3.6D Group Action Factors. C.,. for 4" Shear 

Plate Connectors With Steel Side Plates 64 

11. 2A Lag Screw Withdrawal Design 

Values (W) ,. 68 

1 1 . 2B Cut Thre ad or Rolled Thread Wood 

Screw Withdrawal Design Values (W) ......... 69 

1 1 .2C Nail and Spike Withdrawal Design 

Values (W) s . 70 

1 1 .3. 1 A Yield Limit Equations 71 

1 1 . 3 . 1 B Reduction Terms 72 

1 1.3.2 Dowel Bearing Strengths 73 

1 1.3.2A Assigned Specific Gravities 74 

1 1 .3.2B Dowel Bearing Strengths for Wood 

Structural Panels 75 

1 1 .5. 1 A Edge Distance Requirements 76 

1 1.5. IB End Distance Requirements 77 

1 1 .5. IC Spacing Requirements for Fasteners 

in a Row 78 

1 1.5. ID Spacing Requirements Between Rows 78 

1 1.5. IE Edge and End Distance and Spacing 

Requirements for Lag Screws Loaded in 
Withdrawal and Not Loaded Laterally 78 

1 1 A BOLTS: Design Values (Z) for Single 
Shear (two member) Connections lor 
Sawn Lumber or SCL with both 
members of identical specific gravity 80 

1 1 B BOLTS: Design Values (Z) for Single 
Shear (two member) Connections for 
Sawn Lumber or SCL with 1/4" ASTM 
A3 6 steel side plate 82 



AMERICAN FOREST & PAPER ASSOCIATION 



NDS2002 FM.pmd 




3/1 3/02. 11:00 AM 



LIST OF TABLES 



1 IC BOLTS: Design Values (Z) for Single 
Shear (two member) Connections for 
Glued Laminated Timber main member 
with sawn lumber side member of 
identical specific gravity 83 

1 1 D BOLTS: Design Values (Z) for Single 
Shear (two member) Connections for 
Glued Laminated Timber with 1/4" 
ASTxM A36 steel side plate 84 

1 IE BOLTS: Design Values (Z) for Single 
Shear (two member) Connections for 
Sawn Lumber or SCL to concrete 85 

1 IF BOLTS: Design Values (Z) lor Double 
Shear (three member) Connections for 
Sawn Lumber or SCL with both members 
of identical specific gravity 86 

1 1G BOLTS: Design Values (Z) for Double 
Shear (three member) Connections for 
Sawn Lumber or SCL with 1/4" ASTM 
A36 steel side plate 88 

1 1 H BOLTS: Design Values (Z) lor Double 
Shear (three member) Connections for 
Glued Laminated Timber main member 
with sawn lumber side member of 
identical species 89 

1 1 1 BOLTS: Design Values (Z) lor Double 
Shear (three member) Connections for 
Glued Laminated Timber with 1/4" 
ASTM A36 steel side plate 90 

1 1 .) LAG SCREWS: Design Values (Z) for 
Single Shear (two member) Connections 
for Sawn Lumber or SCL with both 
members of identical specific gravity 92 

1 1 K LAG SCREWS : Design Values (Z) for 
Single Shear (two member) Connections 
with 1/4" ASTM A36 steel side plate, or 
ASTM A 653. Grade 33 steel side plate 
(ior t s <l/4") 94 

1 1 L WOO D S C RE W S : Design Val u es ( Z ) ior 
Single Shear (two member) Connections 
for Sawn Lumber or SCL with both 
members of identical specific gravity 95 

1 1M WOOD SCREWS: Design Values (Z) for 
Single Shear (two member) Connections 
with ASTM A653, Grade 33 steel side 
plate 96 



1 1 N COMMON WIRE, BOX. or SINKER 
NAILS: Design Values (Z) lor Single 
Shear (two member) Connections lor 
sawn lumber or SCL with both members 
of identical specific gravity 97 

1 J P COMMON WIRE, BOX. or SINKER 
NAILS: Design Values (Z) ior Single 
Shear (two member) Connections with 
ASTM A653, Grade 33 steel side plates 98 

1 1 Q COMMON WIRE, BOX. or SIN KER 

NAILS: Design Values (Z) for Single Shear 
(two member) Connections with Wood 
Structural Panel side members with an 
effective G - 0.50 100 

1 1 R COMMON WIRE, BOX. or SINKER 

NAILS: Design Values (Zj for Single Shear 
(two member) Connections with Wood 
Structural Panel side members with an 
effective G - 0.42 101 

12A Species Groups for Split Ring and 

Shear Plate Connectors 105 

12.2A Split Ring Connector Lnit Design 

Values...^ „ 106 

12.2B Shear Plate Connector Unit Design 

Values s 107 

12.2.3 Penetration Depth Factor. C d . for Split 
Ring and Shear Plate Connectors Used 

with Lag Screws ..108 

12.2.4 Metal Side Plate Factors. C w . for 4" 
Shear Plate Connectors Loaded 

Parallel to Grain 108 

12.3 Geometry Factors. C A , for Split Ring 

and Shear Plate Connectors 113 

13.2.3 Metal Side Plate Factor. C\ ( . lor Timber 

Rivet Connections 117 

13.3.2 Minimum End and Edge Distances for 

Timber Rivet Joints 1 18 

1 3. 2. 1 A Nominal Wood Capacity Parallel to 
Grain, P w , for Timber Rivets (Rivet 
Length - 1-1/2" s p = 1" s q = 1") 1 19 

1 3 . 2 . 1 B Nominal Wood Capacity Parallel to 
Grain, P w , for Timber Rivets (Rivet 
Length - 1-1/2" s p = 1-1/2" s q = 1") 120 



AMERICAN WOOD COUNCIL 



NDS2002 FM.pmd 




3/1 3/02. 11:00 AM 



NATIONAL DESIGN SPECIFICATION FOR WOOD CONSTRUCTION 



1 3.2. 1 C Nominal Wood Capacity Parallel to 
Grain, P w . lor Timber Rivets (Rivet 
Length - 2-1/2" s p = 1" 1") 121 

13,2. ID Nominal Wood Capacity Parallel to 
Grain, P tt .. lor Timber Rivets (Rivet 
Length - 2-1/2" s,, - 1-1/2" s q = 1") 122 

13.2. IE Nomina] Wood Capacity Parallel to 
Grain. P w , lor Timber Rivets (Rivet 
Length = 3-1/2" ^-f s q = 1") 123 

13.2. IF Nominal Wood Capacity Parallel to 
Grain. P tt . lor Timber Rivets (Rivet 
Length = 3-1/2" s„ = 1-1/2" s q = 1") 124 

13.2.2A Values of q w (lbs.) Perpendicular to 

Grain lor Timber Rivets 125 

13.2.2B Geometry Factor. C A . for Timber Rivet 
Connections Loaded Perpendicular to 
Grain 125 



15. 1 . 1 Lateral Distribution Factors for 

Moment 1 32 

15. 1 .2 Lateral Distribution in Terms of 
Proportion of Total Load 132 

16.2.1 Effective Char Rates and Char Layer 
Thicknesses (lor p„ = 1.5 in./hr.) 140 

16.2.2 Adjustment Factors for Fire Design... 141 

Fl Coefficients of Variation in Modulus of 
Elasticity (GOV. : for Lumber and Glued 
Laminated Timber 154 

G 1 Buckling Length Coefficients. K.. 1 56 

11 Fastener Bending Yield Strengths, F„ e 160 



LIST OF TABLES IN THE NDS SUPPLEMENT 



1A Nominal and Minimum Dressed Sizes of 

Sawn Lumber 13 

IB Section Properties of Standard Dressed 

(S4S) Sawn Lumber , 14 

1 C Section Pro pert i e s of Western Species Glued 

Laminated Timber 16 

1 D Section Properties of Southern Pine Glued 

Laminated Timber 22 

4 A Base Design Values for Visually Graded 

Dimension Lumber (2"-4" thick) (All species 
except Southern Pine) 30 

4B Design Values for Visually Graded Southern 

Pine Dimension Lumber (2"-4" thick) 36 

4C Design Values for Mechanically Graded 

Dimension Lumber 39 

4D Design Values for Visually Graded Timbers 

(5" x 5" and larger) 43 



4E Design Values for Visually Graded Decking 50 

4F Base Design Values for Non-North American 
Visually Graded Dimension Lumber 
(2"-4" thick) 53 

5A Design Values for Structural Glued 

Laminated Softwood Timber (Members 

stressed primarily in bending) 57 

5B Design Values for Structural Glued 

Laminated Softwood Timber (Members 
stressed primarily in axial tension or 
compression) 63 

5C Design Values for Structural Glued 

Laminated Hardwood Timber (Members 

stressed primarily in bending) ...68 

5D Design Values for Structural Glued 

Laminated Hardwood Timber (Members 
stressed primarily in axial tension or 
compression) 70 



AMERICAN FOREST & PAPER ASSOCIATION 



NDS2002 FM.pmd 




3/1 3/02. 11:00 AM 




NATIONAL DESIGN SPECIFICATION FOR WOOD CONSTRUCTION 



LIST OF FIGURES 



3 A Spacing of Staggered Fasteners 12 

3B Net Cross Section at a Split Ring or Shear 

Plate Connection 12 

3D Shear at Supports 16 

3E Bending Member End-Notched on 

Compression Face... 17 

3F Effective Depth, d L „ of Members a! 

Connections 1 7 

3G Simple Solid Column 18 

3H Combined Bending and Axial Fension 21 

31 Combined Bending and Axial Compression .... 2 1 

3.1 Bearing at an Angle to Grain 22 

4A Notch Limitations lor Sawn Lumber Beams ... 29 

5A Curved Bending Member 35 

10A Eccentric Connections 56 

10B Group Action lor Staggered Fasteners 61 

1 1 A Toe-Nail Connection ...67 

1 1 B Single Shear Bolted Connection 72 

1 1C Double Shear Bolted Connections 72 

1 1 D Multiple Shear Bolted Connection 75 

1 IE Shear Area for Boiled Connections 75 

1 IF Combined Lateral and Withdrawal Loading .... 76 

1 1G Bolted Connection Geometry 77 

1 1 H Spacing Between Outer Rows of Bolts 78 

12A Split Ring Connector 104 

12B Pressed Steel Shear Plate Connector 104 

12C Malleable Iron Shear Plate Connector 104 

12D Axis of Cut for Symmetrica! Sloping 

End Cut ". 109 

12E Axis of Cut for Asymmetrical Sloping 

End Cut 109 

12F Square End Cut 110 



12G Sloping End Cut with Load Parallel to Axis 

of Cut (cp=0 a ) 110 

12H Sloping End Cut with Load Perpendicular to 

Axis of Cut ((p=90°) 110 

121 Sloping End Cut with Load at an Angle <p 

to Axis of Cut 110 

12J Connection Geometry for Split Rings and 

Shear Plates Ill 

t'2K End Distance for Members with Sloping 

End Cut 1 1 1 

13A End and Edge Distance Requirements for 

Timber Rivet Joints .....118 

14.4.1 Diaphragm Length and Width 129 

ISA Spaced Column Joined by Split Ring or 

Shear Plate Connectors 133 

15B Mechanically Laminated Built-up Column ... 135 

15C Typical Nailing Schedules for Built-up 

Columns 136 

15D Typical Bolting Schedules for Built-up 

Columns 136 

15E Eccentrically Loaded Column L 38 

B 1 Load Duration Factors, C D , for Various 

Load Durations 147 

E I Staggered Rows of Bolts 1 5 1 

E2 Single Row of Bolts 1 52 

E3 Single Row of Split Ring Connectors 153 

11 Connection Yield Modes 159 

J I Solution of Hankinson Formula 163 

J2 Connection Loaded at an Angle to Grain 163 



AMERICAN WOOD COUNCIL 



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AMERICAN 

WOOD 

COUNCIL 



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2001 EDITION 









SUPPLE 



E N T 




NATIONAL! DESIGN SPECIFICATION 



DESIGN VALUES FOR 
WOOD CONSTRUCTION 



American 
Forest & 
Paper 
Association 



American Wood Council 




SUPPLEMENT 




NATIONAL DESIGN SPECIFICATION 9 

DESIGN VALUES FOR 
WOOD CONSTRUCTION 



Copyright © 200 1 
American Forest & Paper Association, Inc. 



Supp FM Draft.pmd 




3/1 1, '02. 10:19 AM 



DESIGN VALUES FOR WOOD CONSTRUCTION - NDS SUPPLEMENT 




Introduction 



This Supplement is an integral part of the National 
Design Specification" (NDS") for Wood Construction, 
200 1 Edition. It provides design values for structural sawn 
lumber and struetural glued laminated limber. 

Lumber 

The design values for lumber in this Supplement are 
obtained from grading rules published by seven agencies: 
National Lumber Grades Authority (a Canadian agency), 
Northeastern Lumber Manufacturers Association. North- 
ern Softwood Lumber Bureau, Redwood Inspection 
Service, Southern Pine Inspection Bureau, West Coast 
Lumber Inspection Bureau and Western Wood Products 
Association. The grading rules promulgated by these agen- 
cies, including the design values therein, have been 
approved by the Board of Review of the American Lum- 
ber Standards Committee and certified for conformance 
with U.S. Department of Commerce Voluntary Product 
Standard PS 20-99, (American Softwood Lumber Stan- 
dard). 

Design values for most species and grades of visually 
graded dimension lumber are based on the provisions of 
ASTM Standard D1990-00 Fl (Establishing Allowable Prop- 
erties for Visually Graded Dimension Lumber from 
In-Grade Tests of Full-Size Specimens). Design values 
for visually graded timbers, decking, and some species and 
grades of dimension lumber are based on the provisions of 
ASTM Standard D245-00' ' (Establishing Structural Grades 
and Related Allowable Properties for Visually Graded Lum- 
ber). The methods in ASTM Standard D245-00 fl involve 
adjusting the strength properties of small clear specimens 
of wood, as given in ASTM Standard D2555-98 (Estab- 
lishing Clear Wood Strength Values), for the effects of 
knots, slope of grain, splits, checks, size, duration of load, 
moisture content and other inlluencing factors, to obtain 
design values applicable to normal conditions of service. 
Lumber structures designed on the basis of working 
stresses derived from ASTM Standard D245 procedures 
and standard design criteria have a long history of satis- 
f a c t ory perform a nc e . 

Design values for machine stress rated (MSR) lum- 
ber and machine evaluated lumber (MEL) are based on 
nondestructive testing of individual pieces. Certain visual 
grade requirements also apply to such lumber. The stress 
rating system used for V1SR and MEL lumber is regularly 
checked by the responsible grading agency for conform- 
ance to established certification and quality control 
procedures. 



For additional information on development and appli- 
cability of lumber design values, the grading rules published 
by the individual agencies and the referenced ASTM Stan- 
dards should be consulted. 

Glued Laminated Timber 

Design values in this Supplement for glued laminated 
timber are developed and published by the American In- 
stitute of Timber Construction (AITC) and APA— The 
Engineered Wood Association (APA) in accordance with 
principles originally established by the U.S. Forest Prod- 
ucts Laboratory in the early 1950s. These principles involve 
adjusting strength properties of clear straight grained lum- 
ber to account for knots, slope of grain, density, size of 
member, number of laminations and other factors unique 
to laminated limber. 

Specific methods used to establish design values have 
been periodically revised and improved to rellecl the results 
of tests of large glued laminated timber members conducted 
by the U.S. Forest Products Laboratory and other accred- 
ited testing agencies. The performance history of structures 
made with glued laminated timber conforming to AITC 
specifications and manufactured in accordance with Ameri- 
can National Standard AN SI/ AITC A 1 90. 1 - 1 992 (Structural 
Glued Laminated Timber) has demonstrated the validity of 
the methods used to establish glued laminated timber design 
values. 

Conditions of Use 

Design values presented in this Supplement are for 
normal load duration under dry conditions of service. Be- 
cause the strength of wood varies with conditions under 
which it is used, these design values should only be applied 
in conjunction with appropriate design and service recom- 
mendations from the NDS. Additionally, the design values 
in this Supplement apply only to material identified by the 
grade mark of, or certificate of inspection issued by, a grad- 
ing or inspection bureau or agency recognized as being 
competent. 



AMERICAN WOOD COUNCIL 



Supp FM Draft.pmd 




3/1 1, '02. 10:19 AM 



DESIGN VALUES FOR WOOD CONSTRUCTION - NDS SUPPLEMENT 



TABLE OF CONTENTS 



Chapter Tille Page 

1 Sawn Lumber Grading 
Agencies 1 

1 . 1 List of Sawn Lumber Grading Agencies 

2 Species Combinations 3 

2. 1 List of Sawn Lumber Species 
Combinations 4 

2.2 List of Non-North American Sawn 
Lumber Species Combinations 7 

2.3 List of Structural Glued Laminated 
Timber Species Combinations 8 



Chapter ■TilL- Page 

3 Section Properties 11 

3.1 Section Properties of Sawn Lumber 
and Glued Laminated Timber 

4 Design Values 29 



LIST OF TABLES 



l A Nominal and Minimum Dressed Sizes ol 

Sawn Lumber 13 

1 B Section Properties of Standard Dressed 

(S4S) Sawn Lumber 14 

1 C Section Properties of Western Species Glued 

Laminated Timber 16 

1 D Section Properties of Southern Pine Glued 

Laminated Timber 22 

4 A Base Design Values for Visually Graded 

Dimension Lumber (2"-4" thick) (All species 
except Southern Pine) 30 

4B Design Values for Visually Graded Southern 

Pine Dimension Lumber (2"-4" thick) 36 

4C Design Values for Mechanically Graded 

Dimension Lumber 39 

4D Design Values for Visually Graded Timbers 

(5" x 5" and larger) 43 

4E Design Values for Visually Graded Decking ...50 



4L Base Design Values lor Non-North American 



Visually Graded Dimension Lumber 

(2"-4" thick) 53 

5 A Design Values for Structural Glued 

Laminated Softwood Timber (Members 
stressed primarily in bending) 57 

5B Design Values lor Structural Glued 

Laminated Softwood Timber (Members 
stressed primarily in axial tension or 
compression) 63 

5C Design Values for Structural Glued 

Laminated Hardwood Timber (Members 
stressed primarily in bending) 68 

5D Design Values for Structural Glued 

Laminated Hardwood Timber (Members 
stressed primarily in axial tension or 
compression) 70 



AMERICAN FOREST & PAPER ASSOCIATION 



Supp FM Draft.pmd 




3/1 1, '02. 10:19 AM 




AMERICAN WOOD COUNCIL 



Supp FM Draft.pmd 




3/1 1, '02. 10:19 AM